Flexible pipe including thermal insulation

ABSTRACT

Apparatus for providing a thermal insulation layer in a flexible pipe, including one or more encapsulated regions of aerogel material disposed in a layer of flexible pipe body is disclosed. In addition, flexible pipe body including such apparatus, and a method of manufacturing flexible pipe body is disclosed.

The present invention relates to a method and apparatus for providingone or more thermally insulating layers in a flexible pipe. Inparticular, but not exclusively, the present invention relates to theuse of one or more encapsulated regions of aerogel material disposed inone or more layers of flexible pipe body.

Traditionally flexible pipe is utilised to transport production fluids,such as oil and/or gas and/or water, from one location to another.Flexible pipe is particularly useful in connecting a sub-sea location toa further sub-sea location or sea level location. Flexible pipe isgenerally formed as an assembly of flexible pipe body and one or moreend fittings. The pipe body is typically formed as an assembly oflayered materials that form a fluid and pressure-containing conduit. Thepipe structure allows large deflections without causing bending stressesthat impair the pipe's functionality over its lifetime. The pipe body isgenerally, but not necessarily, built up as a composite structureincluding unbonded metallic and polymer layers.

Such unbonded flexible pipe has been an enabler for deep water (lessthan 3300 feet (1005.84 metres)) and ultra-deep water (greater than 3300feet) developments for over 15 years. Available technology enabled theindustry to initially produce in deep water in the early 90s and inultra-deep waters up to around 6500 feet (1981.2 metres) in the late90s. Water depths greater than 6500 feet push the envelope where typicalfree hanging riser configurations and flexible pipe in general canoperate.

It is the increasing demand for oil which is causing exploration tooccur in environments and at depths where environmental factors are moreextreme. In such deep and ultra-deep water environments ocean floortemperature increases the risk of production fluids cooling to atemperature which may lead to pipe blockage. For example, whentransporting crude oil blockage of the internal bore of the flexiblepipe can occur due to paraffin formation. As a method to overcome suchproblems it has in the past been suggested that a layer of thermalinsulation should be provided around a fluid retaining layer of aflexible pipe. Such a fluid retaining layer, often termed a barrierlayer or alternatively a liner, forms an inner bore along which fluid istransported. Thermal insulation has been somewhat effective ininsulating the inner bore of the pipe from external low temperature thushelping prevent blockage. Nevertheless the insulating effects providedto date have been limited.

Occasionally as an alternative a cold fluid is transported along thebore of the flexible pipe. Again it is helpful to thermally insulatesuch fluids to prevent undesired heating from the surrounding relativelywarm environment.

A known prior art technique for providing a thermal insulation layer isto wind tape manufactured from a thermally insulating material helicallyaround an underlying layer during manufacturing of flexible pipe body.Sometimes a tape formed from a polypropylene matrix with hollow glassspheres has been used which provides a low thermal conductivity (k)value and which is able to withstand reasonably high hydrostaticpressures. However, the hollow glass spheres in the tape are prone tocrushing and internal and external pressures operate to squeeze the tapelayer thereby reducing thickness and thus thermal insulation effects.

A further prior art technique for providing a thermal insulation layeris to extrude a layer of thermally insulating material over anunderlying layer during manufacturing of flexible pipe body. Commonly apolymer matrix containing air bubbles and/or glass spheres has beenused. However, this includes an additional and complicated manufacturingstep which can be a complex process involving careful alignment, heatingand cooling steps during manufacture. Also geometric tolerances aredifficult to control during an extrusion process and this can have aknock on effect to subsequent layers formed radially outside such anextruded layer.

With either the tape or extruded layer technique mentioned above thematerials used have until now limited the thermal conductivity (k) valueavailable.

It is an aim of the present invention to at least partly mitigate theabove-mentioned problems.

It is an aim of certain embodiments of the present invention to provideflexible pipe body which can be used to form a flexible pipe of a typeable to transport production fluids and which includes at least onethermal insulation layer offering a much reduced path for thermalconduction relative to prior art flexible pipe body.

It is an aim of certain embodiments of the present invention to provideflexible pipe body having thermal insulation in a carcass layer and/orbetween a carcass layer and a barrier layer.

It is an aim of embodiments of the present invention to provide a riserassembly, jumper, flow line and/or method of manufacturing a flexiblepipe able to operate in deep and ultra-deep water environments.

According to a first aspect of the present invention there is providedapparatus for providing a thermal insulation layer in a flexible pipe,comprising:

-   -   one or more encapsulated regions of aerogel material disposed in        a layer of flexible pipe body.

According to a second aspect of the present invention there is provideda method of manufacturing flexible pipe body, comprising the steps of:

-   -   providing one or more encapsulated regions of thermally        insulating aerogel material in a layer of flexible pipe body.

According to a third aspect of the present invention there is provideduse of one or more regions of encapsulated aerogel material in a layerof a flexible pipe.

According to a fourth aspect of the present invention there is providedapparatus for providing a thermal insulation layer in a flexible pipe,comprising:

-   -   one or more encapsulated regions of insulating material disposed        in a layer of flexible pipe body.

According to a fifth aspect of the present invention there is provided atape for providing a layer in flexible pipe body, comprising:

-   -   an elongate tape body portion, a cross section of the tape        through the body portion comprising at least one channel region        holding aerogel material.

Certain embodiments of the present invention provide flexible pipe bodyin which at least one layer is formed substantially of aerogel material.Aerogel material has a very low thermal conductivity (k) value and thusprovides a highly efficient insulation layer.

Certain embodiments of the present invention provide flexible pipe bodyin which a thermal insulation layer is formed immediately radiallyinside of a fluid retaining layer. This retains heat in the inner boreof the flexible pipe. Alternatively should the flexible pipe be utilisedto transport cold fluids such as liquid nitrogen the thermal insulationlayer thus operates to prevent undesired heating in the bore region.

Certain embodiments of the present invention provide flexible pipe bodyin which a thermal insulation layer is formed close to the outer sheathof a flexible pipe body. This retains heat within the majority of thelayers of the flexible pipe in the instance that a hot fluid istransported. Alternatively location of such a thermal insulation layerassists in keeping multiple layers within the flexible pipe body cool ifa cold fluid is transported.

Embodiments of the present invention will now be described hereinafter,by way of example only, with reference to the accompanying drawings inwhich:

FIG. 1 illustrates a flexible pipe body;

FIG. 2 illustrates a catenary riser, flow line and jumper;

FIG. 3 illustrates a carcass layer including regions of thermalinsulation material;

FIG. 4 illustrates windings in the carcass layer of FIG. 3;

FIG. 5 illustrates an alternative carcass layer including regions ofthermal insulation material;

FIG. 6 illustrates a carcass layer including regions of thermalinsulation material;

FIG. 7 illustrates windings in the carcass layer of FIG. 6;

FIG. 8 illustrates interlocking of carcass layer windings;

FIG. 9 illustrates an insulating tape;

FIG. 10 illustrates how the insulating tape shown in FIG. 9 can bewound;

FIG. 11 illustrates how the insulating tape shown in FIG. 9 can bewound;

FIG. 12 illustrates a carcass layer;

FIG. 13 illustrates the carcass layer of FIG. 12 including filledchannel regions;

FIG. 14 illustrates an alternative carcass layer;

FIG. 15 illustrates a hoop element;

FIG. 16 illustrates interlocked hoop elements;

FIG. 17 illustrates alternative hoop elements interlocked;

FIG. 18 illustrates alternative interlocked hoop elements;

FIG. 19 illustrates interlocked hoop elements;

FIG. 20 illustrates hoops with fins; and

FIG. 21 illustrates hoops with strengthening beams.

In the drawings like reference numerals refer to like parts.

Throughout this specification reference will be made to a flexible pipe.It will be understood that a flexible pipe is an assembly of a portionof pipe body and one or more end fittings in each of which a respectiveend of the pipe body is terminated. FIG. 1 illustrates how pipe body 100is formed in accordance with an embodiment of the present invention froma composite of layered materials that form a pressure-containingconduit. Although a number of particular layers are illustrated in FIG.1, it is to be understood that the present invention is broadlyapplicable to composite pipe body structures including two or morelayers manufactured from a variety of possible materials. It is to befurther noted that the layer thicknesses are shown for illustrativepurposes only.

As illustrated in FIG. 1, a pipe body includes an optional innermostcarcass layer 101. The carcass provides an interlocked construction thatcan be used as the innermost layer to prevent, totally or partially,collapse of an internal pressure sheath 102 due to pipe decompression,external pressure, and tensile armour pressure and mechanical crushingloads. It will be appreciated that certain embodiments of the presentinvention are applicable to ‘smooth bore’ as well as such ‘rough bore’applications.

The internal pressure sheath 102 acts as a fluid retaining layer andcomprises a polymer layer that ensures internal-fluid integrity. It isto be understood that this layer may itself comprise a number ofsub-layers. It will be appreciated that when the optional carcass layeris utilised the internal pressure sheath is often referred to by thoseskilled in the art as a barrier layer. In operation without such acarcass (so-called smooth-bore operation) the internal pressure sheathmay be referred to as a liner.

An optional pressure armour layer 103 is a structural layer with a layangle close to 90° that increases the resistance of the flexible pipe tointernal and external pressure and mechanical crushing loads. The layeralso structurally supports the internal-pressure sheath.

The flexible pipe body also includes an optional first tensile armourlayer 104 and optional second tensile armour layer 105. Each tensilearmour layer is a structural layer with a lay angle typically between20° and 55°. Each layer is used to sustain tensile loads and internalpressure. The tensile armour layers are counter-wound in pairs.

The flexible pipe body shown also includes optional layers 106 of tapewhich help contain underlying layers and to some extent prevent abrasionbetween adjacent layers.

The flexible pipe body also typically includes an optional outer sheath107 which comprises a polymer layer used to protect the pipe againstpenetration of seawater and other external environments, corrosion,abrasion and mechanical damage.

Each flexible pipe comprises at least one portion, sometimes referred toas a segment or section of pipe body 100 together with an end fittinglocated at at least one end of the flexible pipe. An end fittingprovides a mechanical device which forms the transition between theflexible pipe body and a connector. The different pipe layers as shown,for example, in FIG. 1 are terminated in the end fitting in such a wayas to transfer the load between the flexible pipe and the connector.

FIG. 2 illustrates a riser assembly 200 suitable for transportingproduction fluid such as oil and/or gas and/or water from a sub-sealocation 201 to a floating facility 202. For example, in FIG. 2 thesub-sea location 201 includes a sub-sea flow line. The flexible flowline 205 comprises a flexible pipe, wholly or in part, resting on thesea floor 204 or buried below the sea floor and used in a staticapplication. The floating facility may be provided by a platform and/orbuoy or, as illustrated in FIG. 2, a ship. The riser 200 is provided asa flexible riser, that is to say a flexible pipe connecting the ship tothe sea floor installation.

It will be appreciated that there are different types of riser, as iswell-known by those skilled in the art. Embodiments of the presentinvention may be used with any type of riser, such as a freely suspended(free, catenary riser), a riser restrained to some extent (buoys,chains), totally restrained riser or enclosed in a tube (I or J tubes).

FIG. 2 also illustrates how portions of flexible pipe body can beutilised as a flow line 205 or jumper 206.

FIG. 3 illustrates a carcass layer 101 made by helically winding a tape300 so that adjacent windings can interlock. The tape 300 has asubstantially Z shape and the body of the tape is hollow. The body maybe almost wholly hollow in which case the body acts like a shell (asshown in FIG. 3) or alternatively may be only partially hollow so thatonly a region of the cross section is hollow or multiple separateregions are left hollow. The body of the tape thus encapsulates at leastone channel region within the tape. This channel region 301 is filledwith an insulating aerogel material 350. Alternatively the channelregion can be filled with another insulating material.

Throughout this description reference is made to an aerogel material.Certain aerogel materials are open-celled, mesoporous, solid foams thatare composed of a network of interconnected nanostructures and whichexhibit a porosity (non-solid volume) of no less than 50%. It will beunderstood that the term “mesoporous” refers to a material whichcontains pores ranging from 2 to 50 nm in diameter. It will beappreciated that aerogels can be made from a variety of substancesincluding, but not limited to, most of the transition metal oxides (forexample, iron oxide or the like), silica, biological polymers (such aspectin, agar or the like), carbon nanotubes, organic polymers (such asresorcinol-formaldehyde, polyacrylates or the like). Aerogel materialscan be manufactured using many different techniques. For example silicagels are produced using the sol-gel process in which nanoparticlessuspended in a liquid solution are invoked to interconnect and form acontinuous, porous, nanostructured network of particles across thevolume of the liquid medium.

It will be understood that the term aerogel refers to a material thathas a very low coefficient of thermal conduction. That is to say of 0.05W/mK or less. Aptly 0.02 W/mK or less.

Aerogel materials tend to be hydrophilic but can be made hydrophobic bythe addition of waterproofing substances such astrimethylsilyl-Si(CH₃)₃. Typical thermal conductivity for aerogels isbetween 0.004 W/mK to 0.04 W/mK. This is in comparison to typicalinsulating (but non aerogel) materials used in flexible pipetechnologies which have a k value of 0.15 W/mK to 0.18 W/mK.

As illustrated in FIG. 3 adjacent windings of the Z shaped tape 300 areinterlocked by additionally helically winding a connecting tape 303between adjacent windings of the carcass tape. The connecting tapewinding 303 has a generally H shaped cross section.

FIG. 4 illustrates the windings of FIG. 3 in more detail. The woundtapes form a layer extending axially along the length of the flexiblepipe body. The cross section of the carcass tape 300 has an imaginarycentre line C and has an inwardly turned nose 400 at a first edge of thetape. The nose 400 blends into a horizontal region 401 and the tape isthen bent into a substantially linear region 402 which extends firstlytowards the centre line and then away from the centre line. The centralregion 402 of the tape then turns away from the direction of the firstedge into a further horizontal region 403 before bending again intowards the imaginary centre line C terminating in a further nose 404.This further inwardly turned nose forms the other edge of the carcasstape. In terms of the windings shown in FIG. 4 the first nose is turneddownwardly towards the imaginary centre line and the further nose isturned upwardly towards the imaginary centre line. It will beappreciated that whilst the noses shown in this and further exampleshave rounded ends, other shaped ends are useable.

As illustrated in FIG. 4, the connecting tape 303 has a substantiallyH-shaped cross section providing an upwardly facing substantiallyhorizontal riding surface 410 and an opposed substantially parallelspaced apart downwardly facing substantially horizontal further ridingsurface 412. As illustrated in FIG. 4 an upwardly turned nose 404 of afirst winding rides against the downwardly facing horizontal ridingsurface 412 of the connecting tape between ends which act as abutmentsurfaces 413 which form boundaries to the riding surface. This allowsfor some lateral motion between adjacent windings. A downwardly turnednose 400 of an adjacent winding is able to ride on the upward facingriding surface 410 of the H-shaped connector tape between respectiveabutment surfaces 414 which form side boundaries to the riding surface.

The carcass tape is preformed prior to winding to manufacture a carcasslayer and a channel formed within the body of the tape is filled withaerogel material. In this way the body of the tape encapsulates aerogelmaterial. As consecutive windings are wound and interlocked togetherwith the connecting tape the effect is that one or more encapsulatedregions of aerogel material are laid out in a layer along the axiallength of the flexible pipe body.

It will be appreciated that during manufacture of the carcass tape (thatis to say before the stage of manufacturing flexible pipe) the channelregion within the tape can optionally first be evacuated to help reducethermal conductivity across the tape. Also the use of rigid material(such as metal or composite materials or the like) to manufacture thebody of the tape means that low density aerogels may optionally be usedsince the rigidity of the tape material acts as a housing to give thetape strength.

FIG. 5 illustrates an alternative to the carcass layer illustrated inFIGS. 3 and 4 in which adjacent windings of the carcass layer tape areinterlocked by nesting a hook region of one winding into a valley regionof an adjacent winding. The connecting tape is thus not required.

As illustrated in FIG. 5 a carcass layer 101 is formed by helicallywinding a tape 490 so that adjacent windings can interlock. The crosssection of the carcass tape 490 is a substantially Z-shape and the bodyof the tape is wholly or partially hollow. As with the previous examplethe body can be a shell encapsulating a single channel or can definemore than one channel by having a partially filled body cavity region.The body of the tape thus encapsulates at least one channel regionwithin the tape. This channel region 301 is filled with an insulatingaerogel material or other such insulating material. The wound tape thusforms a layer extending axially along the length of the flexible pipebody. The cross section of the carcass tape 390 has an imaginary centreline C and has an inwardly turned nose 500 at a first edge of the tape.The nose 500 blends into a horizontal region 501 and the tape is thenbent into a substantially linear region 502 firstly towards the centreline and then away from the centre line. The central region 502 of thetape then turns away from the first edge into a further horizontalregion 503 before bending again in towards the imaginary centre line Cterminating in a further nose 504. This further inwardly turned noseforms the other edge of the carcass tape. In terms of the winding shownin FIG. 5 the first nose 500 is turned downwardly towards the imaginarycentre line and the further nose is turned upwardly towards theimaginary centre line.

As illustrated in FIG. 5, adjacent windings of the carcass layer tape490 interlock together. In this sense the first nose and firsthorizontal region 501 and part of the central linear region 502 form ahook portion whilst a remaining portion of the central linear region502, further horizontal portion 503 and further upwardly turned nose 504define a valley region. A nose associated with the hooked portion of awinding nests within the valley region defined by an adjacent winding.The nose of a winding is thus able to ride within a region defined in anadjacent winding between a further nose and a central region of thewinding. This prevents windings in the carcass layer from becomingseparated but allows some lateral motion so that the flexible pipe bodyformed by the carcass layer can flex. Nesting is carried out duringmanufacture as the carcass tape is wound.

The carcass tape 490 is preformed prior to winding to manufacture acarcass layer and a channel formed within the body of the tape is filledwith aerogel material. In this way the body of the tape encapsulatesaerogel material. As windings are wound and interlocked together theeffect is that one or more encapsulated regions of aerogel material arelaid out in a layer of the flexible pipe body.

It will be appreciated that during manufacture of the carcass tape (thatis to say before the stage of manufacturing of flexible pipe) thechannel region within the tape can optionally first be evacuated to helpreduce thermal conductivity across the tape. Also the use of rigidmaterial (such as metal or composite materials or the like) tomanufacture the body of the tape means that low density aerogels mayoptionally be used.

FIG. 6 illustrates an alternative to the carcass layer illustrated inFIGS. 3 to 5. As illustrated in FIG. 6 adjacent windings of a carcasslayer tape having a corrugated cross section can be helically wound tocreate the carcass layer. Adjacent windings are interlocked using aconnecting tape at the interface between adjacent windings.

As illustrated in FIG. 6 a carcass layer 101 is formed by helicallywinding a tape 590 so that adjacent windings are interlocked in somefashion. The cross section of the carcass tape 590 is corrugatedincluding peaks and troughs and the body of the tape is wholly orpartially hollow. The body of the tape thus encapsulates a channelregion which itself has a corrugated shape within the tape. This channelregion 301 is filled with a sheet, having an undulating cross section,of insulating aerogel material. The wound tape thus forms a layerextending axially along the length of the flexible pipe body.

FIG. 7 illustrates the helically wound carcass tape 590 shown in FIG. 6in a cut away format indicating how the carcass layer 101 is formed bywinding a carcass tape 590 helically. The carcass layer tape has acorrugated profile with six complete troughs 700 ₁ to 700 ₆. The troughsare the portions of the corrugations which extend radially innermostwithin the bore defined by the wound tape. The corrugated tape alsoincludes six complete peaks 701 ₁ to 701 ₆ which define the radiallyoutermost parts of the carcass layer. Tape having different numbers ofpeaks and troughs and different pitches to those peaks and troughs showncan of course be used. As windings are wound a connecting tape which hasa substantially H-shaped cross section is also helically woundsimultaneously at the interface between adjacent windings of the carcasslayer tape 494. The cross sectional H-shape of the connecting tape 603is illustrated in FIG. 7. Other connecting tapes having different crosssectional shapes but which permit interlocking can of course be used.

FIG. 8 illustrates a cross section through a region where adjacentwindings of the carcass layer tape 590 are interlocked together. Thecross section of the carcass tape 590 has an imaginary centre line C andhas an inwardly turned nose 800 at a first edge of the tape. The nose800 blends into a horizontal region 801 and the tape is then bent at aninclined angle towards the centre line. A linear region 802 extendsthrough the centre line towards a first trough region which defines aradially innermost fold or corrugation for the carcass tape. At thistrough the tape is bent before extending radially outwardly in a furtherlinear region towards a first peak region 701 ₁. Further peaks andtroughs are laid out across the cross section of the corrugated carcasstape 690. The tape extends from the final peak 701 ₆ into a furtherhorizontal region 803 before bending again in towards the imaginarycentre line C terminating in a further nose 804. This further inwardlyturned nose forms the other edge of the carcass tape. In terms of thewindings shown in FIGS. 6, 7 and 8 the first nose 800 is turneddownwardly towards the imaginary centre line and the further nose 804 isturned upwardly towards the imaginary centre line.

As illustrated in FIG. 8 the connecting tape 603 has a substantiallyH-shaped cross section providing an upwardly facing substantiallyhorizontal riding surface 810 and an opposed substantially parallelspaced apart downwardly facing substantially horizontal further ridingsurface 812. As illustrated in FIG. 8 an upwardly turned nose 804 of afirst winding rides against the downwardly facing horizontal ridingsurface 812 of the connecting tape between abutment surfaces 813 whichform boundaries to the riding surface. This allows for some lateralmotion between adjacent windings. A downwardly turned nose 800 of anadjacent winding is able to ride on the upward facing riding surface 810of the H-shaped connector tape between respective abutment surfaces 814which form side boundaries to the riding surface.

The carcass tape 590 is preformed prior to winding to manufacture acarcass layer and a channel formed within the body of the tape is filledwith aerogel material. In this way the body of the tape encapsulatesaerogel material. One, two or more channels may be formed containingaerogel. As windings are wound and interlocked together with theconnecting tape the effect is that one or more encapsulated regions inthe form of corrugated sheets of aerogel material are laid out in alayer of the flexible pipe body.

It will be appreciated that during manufacture of the carcass tape (thatis to say before the stage of manufacturing flexible pipe) the channelregion within the tape can optionally first be evacuated to help reducedthermal conductivity across the tape. Also the use of rigid materials(such as metal or composite materials or the like) to manufacture thebody of the tape means that low density aerogels may optionally be used.

It will be appreciated that the corrugated carcass tape could bemodified at the nose regions so that adjacent windings of the corrugatedtape interlock in a manner similar to the windings shown in FIG. 5 andwithout the intervening connecting tape being needed.

In addition to providing encapsulated regions of aerogel material in acarcass layer of flexible pipe, tape including aerogel material mayadditionally or optionally be wound at other locations so as to provideone or more layers of thermal insulation as required. For example, alayer of insulating material may be formed immediately inside an outersheath 107 of the flexible pipe body. Such an insulating layer will tendto maintain a warm or cool temperature throughout the multiple layers ofthe flexible pipe body as determined by the temperature of the fluidtransported along the bore of the flexible pipe body. Alternatively, orin addition, an insulating layer may be formed radially immediatelyoutside or inside of the tensile armour layers so as to maintain themetallic parts of those tensile armour layers within a predeterminedtemperature range. Insulating layers may be formed at any other desiredlocation throughout the cross section of the flexible pipe body.

FIG. 9 illustrates a tape 890 in cross section which may be woundhelically around an underlying layer during manufacture of flexible pipebody. As indicated in FIG. 9 the tape 890 has an outer surface 900 whichforms the body to the tape. The body 900 includes a substantially planartop surface spaced apart from and substantially parallel to anunderlying bottom surface 902. Side walls connect the top surface 901and bottom surface 902. The first side wall 903 of the body 900 andfurther side wall 904 of the body 900 together with the top and bottomsurface thus form a shell like body. The central region 905 defined bythe inner surface of the top and bottom surfaces and side walls definesa channel 906. This channel is filled with aerogel material 350.

The tape shown in FIG. 9 can be wrapped helically in a number of ways tocreate a layer in the flexible pipe body. For example as shown in FIG.10 the flexible tape is helically wound in a first layer 1001 withadjacent windings being located side by side. A further layer of tape890 is wound over this first layer 1001 to form an overlying layer 1002.As illustrated in FIG. 10 this overlying layer can lie over theinterconnection of adjacent windings in the layer below. Alternativelythe overlying layer can be wound directly on top of an underlying layer.As a result an insulating layer made from multiple sub layers isgenerated.

FIG. 11 illustrates an alternative way in which the insulating tape 890shown in FIG. 9 can be wound over an underlying layer. As illustrated inFIG. 11 subsequent to a preceding winding being duly wound a subsequentwinding 1101 is wound so that a portion of the subsequent winding 1101lies over an underlying portion of a preceding winding 1102. The neteffect of the two methods illustrated in FIGS. 10 and 11 is that aninsulating layer having a thickness twice that of the thickness I of theinsulating tape 890 is generated. It will be appreciated that if onlyone winding is utilised using the technique shown in FIG. 10 that aninsulating layer having a thickness I is generated.

FIG. 12 illustrates a carcass layer 101 in a length of flexible pipebody in which adjacent windings of a carcass layer tape 1190 interlocktogether. Each winding thus forms an annular element which extendsaround an inner circumference of a bore region. As illustrated in FIG.12 the carcass layer 101 is formed by helically winding the tape 1190 sothat adjacent windings are interlocked. A cross section of the carcasstape 1190 is substantially Z-shaped and the body of the tape is whollyor partially hollow. As with the previously described examples the tapebody can be a shell encapsulating a single channel or can define morethan one channel by having a partially filled body cavity region orplate element separating the central channel. The channel region 1201 isillustrated as being hollow in FIG. 12. Alternatively the channel regioncan be filled with an insulating aerogel material or other suchinsulating material. Alternatively as illustrated in FIG. 13 the channelcan be filled with a strengthening material 1350. For example, thestrengthening element 1350 can be formed of a metal material, such ascarbon, stainless steel or the like, whilst the body of the tape 1190 ismade from a composite material such as glass fibre, carbon fibre,reinforced plastic or the like.

The wound tape thus forms a layer extending axially along the length ofthe flexible pipe body. The cross section of the carcass tape 1190 hasan imaginary centre line C and has an inwardly turned nose 1300 at afirst edge of the tape. The nose 1300 blends into a horizontal region1301 and the tape is then bent into a substantially linear region 1302towards the centre line and then away from the centre line. The centralregion 1302 then turns away from the first edge into a flange region1303. As illustrated in FIG. 12 the tape 1190 is generated from a firstcurved wall and a further curved wall. These are tape elements. The tapeelements shown have a similar and constant cross section. Aptly the tapeelements can have different cross sections, also these may optionally benon-constant. The first curved wall which forms the first nose 1300,horizontal portion 1301, central region 1302 and first flange region1303 is formed spaced apart from the further curved wall in a middleregion thereof. The further curved wall includes an inwardly turned nose1310 which forms a further edge of the carcass tape. This inwardlyturned nose extends into a horizontal region 1311 which then extends intowards the imaginary centre line as a linear region 1312. This linearregion then flares out towards the first edge of the tape forming afurther flange region 1313. The curved walls are integrally formed ormay be separately made and then secured together such as by welding,adhering or the like.

The tape formed by the juxtaposed curved walls may be wound in a helicalfashion to form the carcass layer as will be understood by those skilledin the art. The nose of an outer curved wall and flange region of theinner curved wall form a hook region whilst the nose of the inner curvedwall and flange region of the first curved wall form a valley region. Ahook region of a winding nests within a valley region of an adjacentwinding as the carcass layer is manufactured. The channel region 1201 isformed in the parallel spaced apart region between the inner surfaces ofthe curved walls of the carcass tape. Prior to manufacturing of theflexible pipe body this channel may be filled wholly or partially with adesired material. For example, an aerogel material can be utilised.Alternatively, the channel region is filled with a material having adifferent mechanical property from the body region formed by the curvedwalls of the tape. As a result certain materials can be used to form thetape body whilst the same or different materials can be used to whollyor partially fill the channel region which runs along the centre of thecarcass tape. This allows a manufacturer of the flexible pipe body totailor the materials selected according to the purpose for which theflexible pipe is manufactured. Each winding of the carcass tape forms anannular element which thus extends around an inner circumference of abore region. A channel region is provided within the body portion of thecarcass tape.

The channel region can be filled wholly or partially with one or morematerials having different characteristics. For example, an aerogelmaterial can be used which provides a high degree of insulation to thecarcass layer. Aptly the channel region is substantially filled with amaterial that dissolves within a predicted period of time. Alternativelythe channel can hold a vacuum, an insulating tape containing glassmicrospheres, a foam or the like.

FIG. 14 illustrates an alternative carcass tape to that illustrated inFIGS. 12 and 13. In many respects this carcass tape is similar to thatshown in FIGS. 12 and 13, however, the curved walls of the body of thecarcass tape have elongated horizontal portions 1401, 1411 relative tothe corresponding portions of the carcass tape shown in FIGS. 12 and 13.This enables the channel region in the carcass tape to have a greatervolume per winding and provides a further way in which the physicalcharacteristics of the carcass tape can be modified according to thepurpose for which the flexible pipe including the carcass layer is to beused. The width and/or thickness of the tape, material of the tape bodyand material held in the channel within the tape can be selected asdesired according to the performance parameters needed in the flexiblepipe body. Aptly the width to thickness ratio of the tape is 2:1 orgreater. Aptly the width to thickness ratio is 3:1 or greater.

FIG. 15 illustrates a hoop 1500 which includes a hollow channel region1501 which can be left hollow or which may be filled with an aerogelmaterial or other such insulating material or a strengthening material.Multiple hoops may be aligned next to each other in a side-by-sidecoaxial relationship. The independent hoops can be interlocked togetherwith adjacent hoops being interlocked together so as to form a carcasslayer of a flexible pipe body. The hoop 1500 is an annular element withthe carcass layer when formed comprising adjacent interlocked annularelements each made up of a body portion that extends around an innercircumference of a bore region. A channel region 1501 is provided withinthe body portion of each hoop.

As illustrated in FIG. 15 each hoop element has a circular outersurface. The cross section of the hoop 1500 has an imaginary centre lineC and has a partially inwardly turned nose 1550 at a first edge of thehoop. The nose 1550 blends into a horizontal region 1601 with the outersurface of this horizontal region provided the circular outer crosssection of the hoop. The horizontal region 1601 is then bent towards theimaginary centre line and then away from the centre line in asubstantially linear central region 1602. This central region 1602 isthen turned away from the first edge of the hoop into a flange region1603. As illustrated in FIG. 15 the hoop 1500 is generated from a firstcurved wall and a further curved wall. These are tape elements. The tapeelements shown have a similar and constant cross section. Aptly the tapeelements can have different cross sections and may optionally have anon-constant cross section. The first curved wall which forms the firstnose 1550, horizontal portion 1601, central region 1602 and first flangeregion 1603 is formed spaced apart from the further curved wall in amiddle region thereof. The further curved wall includes an inwardlyturned nose 1610, which forms a further edge to the hoop horizontalportion 16111, which has an inner surface forming the inner surface ofthe hoop. The horizontal region 1611 of the further curved wall bendsfirst towards the imaginary centre line and then continues away from thecentre line in a further linear central region 1612 before being benttowards the first edge of the hoop in a further flange region 1613.

Unlike the generation of a carcass layer by helically winding a tape thecarcass layer of flexible pipe body manufactured with multiple hoopelements of the type shown in FIG. 15 is manufactured by locating hoopelements side-by-side, one-by-one, and bending the nose 1550 at thefirst edge of the hoop over the upstanding nose 1619 of a precedinghoop. FIG. 16 illustrates the nose 1600 bent inwardly from the partiallyinclined position 1550 illustrated in FIG. 15.

The nose of an outer curved wall and flange region of an inner curvedwall form a hook region whilst the nose of the inner curved wall andflange region of the first curved wall form a valley region. A hookregion of a hoop nests within a valley region of an adjacent hoop as thecarcass layer is manufactured. The channel region 1501 is formed in theparallel spaced apart region between the juxtaposed curved walls of thecarcass hoop. Prior to manufacturing of the flexible pipe body thischannel may be filled wholly or partially with a desired material. Forexample, an aerogel material can be utilised. Alternatively, the channelregion is filled with a material having a different mechanical propertyfrom the body region formed by the curved walls of the hoop. As a resultcertain materials can be used to form the hoop body whilst the same ordifferent materials can optionally be used to wholly or partially fillthe channel region which runs along the centre of the hoop. This allowsa manufacturer of the flexible pipe body to tailor the material selectedaccording to the purpose for which the flexible pipe is manufactured.Each independent hoop in the carcass layer forms an annular elementwhich thus extends around an inner circumference of a bore region. Achannel region is provided within the body portion of the carcass hoop.

An advantage of generating a carcass layer using independent hoopelements which are interlocked together with adjacent hoop elements in aside-by-side coaxial relationship, is that the hoop elements may each bemanufactured from different materials. Therefore a profile may begenerated along the length of flexible pipe body having zones withcertain physical characteristics at one region (provided by hoopsmanufactured from the same or similar materials) and one or more furtherzones along the length of the flexible pipe body at desired locationswhere the hoop elements used to manufacture the flexible pipe body inthose zones are manufactured from materials different from the materialsused for the hoop elements in the first zone.

FIG. 17 illustrates how a carcass layer may be manufactured frominterlocking independent hoops having a different cross sectionalprofile from the hoops illustrated in FIGS. 15 and 16. In many respectsthe cross section of the hoop elements shown in FIG. 17 are similar tothose shown in FIGS. 15 and 16. However, the horizontal portions of thefirst curved wall and further curved wall are stretched relative to thecorresponding portions shown in FIGS. 15 and 16. This enables adifferent width to thickness ratio of the hoops to be utilised. Aptlythe width to thickness ratio of the hoop is 2:1 or greater. Aptly thewidth to thickness ratio is 3:1 or greater. The variation of the widthto thickness ratio enables the volume of the channel region to beselected according to environmental factors which the flexible pipe bodywill experience in use.

An advantage of using the hoops shown in FIGS. 15, 16 and 17 tomanufacture a carcass layer is that each hoop element can beindependently manufactured prior to manufacture of the flexible pipebody. These may then be stored until the moment in time when flexiblepipe body is to be manufactured. The materials used to manufacture eachhoop element can be selected according to a physical performancerequired of the hoop. The hoops can be integrally formed or can be madefrom two or more separate walls secured together. These curved walls canbe manufactured from the same or different materials. Each hoop is thuspreformed prior to manufacture of a carcass layer and a channel formedwithin the body of the hoop can be left empty or may be filled with adesired material. If a carcass layer having a high degree of thermalinsulation is required an aerogel material or some other insulatingmaterial may be loaded into the channel. It will be appreciated thatduring manufacture of the hoop the channel region within the hoop canoptionally first be evacuated to help reduce thermal conductivity acrossthe hoop. Also the use of rigid material (such as metal or compositematerials or the like) to manufacture the hoop body means that lowdensity aerogels may optionally be used.

Alternatively the channel region in each hoop can be at least partiallyfilled with a material which will increase the strength of the hoop.That is to say will increase the ability of the hoop to resist crushingforces. The channel region can of course be filled with any materialthat provides a desired physical characteristic to the finished carcasslayer.

FIG. 18 illustrates how hoops 1800 which do not have a channel regioncan be utilised to provide a carcass layer for flexible pipe body. Asillustrated in FIG. 18 a hoop has a substantially S-shape. Each hoopelement 1800 has an imaginary centre line C and a first edge 1801 of ahoop is formed by a horizontal portion 1802 of the hoop element beingbent back partially on itself to form a nose 1803. The horizontalsection 1802 is then bent towards the centre line C at a first bend 1804into a central substantially linear region 1805 which then continuesaway from the centre line until being bent at a further bend region 1806into a further horizontal region 1807. This further horizontal region1807 is substantially parallel to the first horizontal portion 1802 inthe cross section of the hoop 1800. The further horizontal portion isthen bent back upon itself to form a further edge 1808 of the hoop whichextends into an inwardly turned nose 1809.

As illustrated in FIG. 18 multiple hoop elements 1800 ₁, 1800 ₂ . . .1800 _(n) can be aligned in a side-by-side coaxial relationship andinterlocked so as to form a carcass layer in flexible pipe body. Theinwardly turned nose 1803 at a first edge of a hoop interlocks with aninwardly turned nose 1809 in an adjacent hoop to ensure that hoopelements do not become separated during use.

FIG. 19 illustrates how a carcass layer can be manufactured frominterlocked hoops 1900. Each hoop shown in FIG. 19 is formed from afirst curved wall of the type illustrated in FIG. 18 and a juxtaposedmirror image of that curved wall formed as a second curved wall securedor integrally formed with the first curved wall. Each hoop 1900 has animaginary centre line C and an outer part imaginary centre line D₁ andan inner part imaginary centre line D₂. A first edge 1901 of a hoopcomprises twin rings formed by an inner and outer horizontal portion1902 being bent backward to form respective inner and outer noses 1903.Each of the inner and outer horizontal sections 1902 is then bent awayfrom the main centre line C towards a respective imaginary inner orouter centre line D₁, D₂. From a respective central substantially linearregion 1905 a further bend region 1906 is formed which turns each curvedside wall into a respective horizontal region 1907 _(inner), 1907_(outer). This further horizontal region 1907 is substantially parallelto the first horizontal portion 1902. The further horizontal portion isthen bent back upon itself at a further edge 1908 which is formed as twodistinct rings. The bent back horizontal portion forms an inner andouter inwardly turned nose 1909. As will be appreciated by those skilledin the art a carcass layer may be manufactured by interconnecting hoopsone by one or many simultaneously by pushing the edges of the hoopstogether so that the nose regions at a first edge of a hoop interlockwith the nose regions of an adjacent hoop. The hoops may be manufacturedfrom the same or different materials. The curved walls of each hoop maybe integrally formed or may be secured together by welding, gluing,riveting or the like.

FIG. 20 illustrates how hoops having a solid cross section (that is tosay without an internal channel) may be connected together to form acarcass layer. These hoops each have a respective fin 2001 which is aplate extending from an inner surface of the hoop. The hoops may bealigned and interconnected during a manufacturing process so that thefins are exactly aligned in a linear array axially along the length ofthe flexible pipe body. Alternatively, each fin or the fins of a groupof hoops may be radially offset with respect to fins in an adjacent hoopor adjacent group. As a result it will be appreciated that therotational offset between the fins can induce a rotation motion in fluidtransported along the bore of the flexible pipe body. This can beadvantageous in certain environments and/or when certain types oftransport fluid are being transported. Fins can of course be used withhoops previously described which include an internal channel.

FIG. 21 illustrates how multiple hoops may be interlocked together toform a carcass layer of flexible pipe body. As illustrated in FIG. 21the hoops include cross beams 2101 which extend across a diameter of thehoops. Further cross beams 2102 also extend across the diameter of thehoops at right angles to the first cross beams. It will be appreciatedthat each cross beam acts as a strengthening element so as to increasethe crush resistance of each hoop element. One, two or more cross beamsmay be utilised per hoop. The cross beams of hoops interlocked togetherto form a carcass layer may be aligned or may be rotationally offsetwith respect to one another. Alternatively the cross beams of groups ofhoops may be aligned or may be rotationally offset with the cross beamsin other groups of hoop elements. The offsetting of cross beams can beused to induce a rotational motioning fluid transported in the boreregion. Alternatively/additionally the offsetting of cross beams canprovide a flexible pipe body which is resistant to crushing forces atdifferent radial angles. The cross beams can of course alternativelyextend across only part of the hoop rather than extending acrossdiametrically.

Hoops can be made which have a circular outer shape but are filled in sothat an internal bore of the flexible pipe body has a non-circular crosssection.

Throughout the description and claims of this specification, the words“comprise” and “contain” and variations of them mean “including but notlimited to”, and they are not intended to (and do not) exclude othermoieties, additives, components, integers or steps. Throughout thedescription and claims of this specification, the singular encompassesthe plural unless the context otherwise requires. In particular, wherethe indefinite article is used, the specification is to be understood ascontemplating plurality as well as singularity, unless the contextrequires otherwise.

Features, integers, characteristics, compounds, chemical moieties orgroups described in conjunction with a particular aspect, embodiment orexample of the invention are to be understood to be applicable to anyother aspect, embodiment or example described herein unless incompatibletherewith. All of the features disclosed in this specification(including any accompanying claims, abstract and drawings), and/or allof the steps of any method or process so disclosed, may be combined inany combination, except combinations where at least some of suchfeatures and/or steps are mutually exclusive. The invention is notrestricted to the details of any foregoing embodiments. The inventionextends to any novel one, or any novel combination, of the featuresdisclosed in this specification (including any accompanying claims,abstract and drawings), or to any novel one, or any novel combination,of the steps of any method or process so disclosed.

The reader's attention is directed to all papers and documents which arefiled concurrently with or previous to this specification in connectionwith this application and which are open to public inspection with thisspecification, and the contents of all such papers and documents areincorporated herein by reference.

1. Apparatus for providing a thermal insulation layer in a flexiblepipe, comprising: one or more encapsulated regions of aerogel materialdisposed in a layer of flexible pipe body.
 2. The apparatus as claimedin claim 1, further comprising: said one or more regions comprises atleast one encapsulated continuous layer of aerogel material extendingaxially along a portion of the flexible pipe body.
 3. The apparatus asclaimed in claim 1, further comprising: said one or more regionscomprises a plurality of encapsulated sheets of aerogel materialdisposed in a substantially end-to-end configuration each extendingalong a respective portion of the flexible pipe body.
 4. The apparatusas claimed in claim 2, further comprising: at least one inner sleevemember and at least one outer sleeve member coaxial with and spacedapart from the inner sleeve, providing a chamber region therebetween,said chamber region encapsulating and being at least partially filledwith a layer of said aerogel material.
 5. The apparatus as claimed inclaim 4, further comprising: each inner sleeve member and outer sleevemember is substantially cylindrical and said chamber region is anannular region extending coaxially therebetween.
 6. The apparatus asclaimed in claim 4, further comprising: each of the inner sleeve memberand outer sleeve member has a corrugated profile along a respectivelength thereof.
 7. The apparatus as claimed in claim 4, furthercomprising: each inner sleeve member is sealed at a first and second endthereof to a respective first and second end of a respective outersleeve member.
 8. The apparatus as claimed in claim 4, furthercomprising: each inner or outer sleeve member is a metal tube element ormetal portion of a tube element.
 9. The apparatus as claimed in claim 4further comprising a plurality of connecting rings having asubstantially H-shaped cross section, a respective connecting ring beinglocated between sleeve members encapsulating adjacent layers of aerogelmaterial.
 10. The apparatus as claimed in claim 1, further comprising:said one or more regions comprises an encapsulated channel region in across section of a tape forming a helically wound tape layer, saidchannel region being at least partially filled with said aerogelmaterial, adjacent windings and respective encapsulated channel regionsextending as a layer along the flexible pipe body.
 11. The apparatus asclaimed in claim 10, further comprising: the cross section of said tapefurther comprises a valley region and a hook region that interlockadjacent windings in said tape layer.
 12. The apparatus as claimed inclaim 10, further comprising: the cross section of said tape iscorrugated comprising at least one peak and trough region.
 13. Theapparatus as claimed in claim 11, further comprising: a substantiallyH-shaped connecting tape locatable between adjacent windings of saidtape.
 14. The apparatus as claimed in claim 10, further comprising: thecross section of the tape is substantially rectangular.
 15. Theapparatus as claimed in claim 1, further comprising: said one or moreregions comprises an annular channel region in a cross section of a hoopelement, a plurality of said hoop elements being disposed in aside-by-side coaxial relationship to thereby provide said layer. 16.Flexible pipe body comprising the apparatus as claimed in claim
 1. 17.The flexible pipe body as claimed in claim 16, further comprising: saida layer comprises a carcass layer and/or an insulation layer of theflexible pipe body.
 18. The flexible pipe body as claimed in claim 16,further comprising: said a layer comprises a layer radially outside anarmour layer and/or proximate to an inner surface of an outer sheathlayer of the flexible pipe body.
 19. A flexible pipe comprising theflexible pipe body as claimed in claim 16 and one or more end fittings.20. A jumper, riser or flowline comprising the flexible pipe as claimedin claim
 19. 21. A method of manufacturing flexible pipe body,comprising the steps of: providing one or more encapsulated regions ofthermally insulating aerogel material in a layer of flexible pipe body.22. The method as claimed in claim 21, further comprising the steps of:providing said encapsulated regions by disposing one or moreencapsulated layers of aerogel material along a respective portion ofthe flexible pipe body.
 23. The method as claimed in claim 22, furthercomprising the steps of: providing a plurality of encapsulated sheets ofaerogel material in a substantially end-to-end configuration andsecuring juxtaposed encapsulated layers via at least one respectiveH-shaped connecting ring.
 24. The method as claimed in claim 21, furthercomprising the steps of: providing the encapsulated regions by helicallywinding a tape having a cross section including a channel region atleast partially filled with aerogel material around an underlying layerin the flexible pipe body.
 25. The method as claimed in claim 24,further comprising the steps of: interlocking adjacent windings of thetape by nesting a hooked region of a winding into a valley region of anadjacent winding.
 26. The method as claimed in claim 24, furthercomprising the steps of: interlocking adjacent windings bysimultaneously winding a connecting tape at an interface region betweenadjacent windings of the insulation tape.
 27. The method as claimed inclaim 21, further comprising the steps of: providing the encapsulatedregions by interlocking a plurality of hoop elements arranged in aside-by-side substantially coaxial relationship, each hoop elementcomprising an annular channel circling throughout the hoop element. 28.(canceled)
 29. Apparatus for providing a thermal insulation layer in aflexible pipe, comprising: one or more encapsulated regions ofinsulating material disposed in a layer of flexible pipe body.
 30. Atape for providing a layer in flexible pipe body, comprising: anelongate tape body portion, a cross section of the tape through the bodyportion comprising at least one channel region holding aerogel material.31. The tape as claimed in claim 30, further comprising: the crosssection of the tape is corrugated, said channel region holding anundulating sheet of aerogel material.
 32. The tape as claimed in claim30, further comprising: the tape has an imaginary centre line, a nose ata first edge region of the tape being inwardly turned towards the centreline and a further nose at a further edge region of the tape beinginwardly turned towards the centre line.
 33. The tape as claimed inclaim 32, further comprising: the first and further noses are turned inopposite directions.
 34. The tape as claimed in claim 30, furthercomprising: the cross section of the tape is substantially Z-shaped andcomprises a hooked region and a valley region.
 35. (canceled) 36.(canceled)